Microcircuit thick film printers include a squeegee for printing on substrates. As a result, some material is left on the bottom of the printing screen after printing on a substrate, materials such as conductors, resistors, dielectrics, solders, epoxies, tungsten, molybdenum, and others. The conductors contain precious metals, such as gold, silver, and palladium. The resistors contain exotic materials, such as ridium and ruthenium. The dielectrics contain alumina oxide, silica, glass frit, and like materials. If the excess material is not cleaned off the bottom surface of the printing screen, eventually a smudged print is obtained, and it must be wiped off to get a clear print.
Presently, the underside of the printing screen is cleaned by hand, wiping it with a lint-free cloth, urethane foam, and like products using a circular motion or a linear motion. Some wiping machines are available using a web under the screen to wipe clean the screen, and as the wiping action takes place, a take-up mechanism is used to roll up the cloth.
Present devices have a number of drawbacks. First, the excess material is lost in the cleaning cloth or web and cannot be reclaimed and re-used instantly. It can be reclaimed later at extra expense. Secondly, production is slower, and at times, additional personnel are required to perform the wiping operation. Present devices are not available for thick film printers and printers used in microelectronics.
It is the object of the present invention to overcome the aforesaid drawbacks and to provide an automatic screen wiper assembly for wiping and cleaning the underside of the printing screen, which allows the wiped material to be reclaimed and not wasted, which increases production and which reduces the personnel and labor required.